a cog in the machine

例句：

1. 1. The engineer was a cog in the machine that made the new car.
   这位工程师是制造新型汽车的机械中不可或缺的齿轮。
2. 2. The doctor is a cog in the machine of health care.
   医生是医疗保健体系中不可或缺的齿轮。
3. 3. The scientist is a cog in the machine of research and development.
   这位科学家是研究和开发领域中不可或缺的齿轮。